You have to consider loads of things when you have a bid for a player you ideally don't want to sell...
- What prices did similar players go for?
- Were said players older/younger? Had they already proven themselves as he has in the Premier League?
- What's his contract situation like? A quick Google search tells me he's contracted until the summer of 2019.
- If we sold him, how much would we need to pay to get somebody of his quality in? Could we even attract somebody as good as him?
- Once a bid has been made and he is aware of it, what's his mindset? Has he indicated he'd like to move? Would 'forcing' him to stay be beneficial to the club and would he be able to forget about it and carry on?
- Who would be the buying club? If we're looking at the 'megarich' Uniteds, Citys, Real Madrids of the world you can add an extra few million on top of his price.
- Do we want to sell? If not then it's above 'market' value of the above criteria.
25m would do it for me. Buys us a solid right back and can get a top striker in. Sorted. Be a shame to see him go like.